Photographic reversal materials containing organic desensitizing compounds



United States Patent Int. Cl. G03c N28 US. Cl. 96-101 34 Claims ABSTRACTOF THE DISCLOSURE Very high speed direct-positive photographic emulsionscomprising silver halide grains fogged with both reduction and goldfogging agents are described. For some applications other foggingagents, e.g. compounds of metals more electropositive than silver, canbe substituted for the gold fogging agent. Photographic elementsemploying such emulsions and processes for preparing them are alsodisclosed.

This application is a continuation-in-part of Illingsworth US.application Ser. No. 533,448, filed Mar. 11, 1966 and entitledPhotographic Materials.

This invention relates to photographic materials, their preparation anduse. In one of its aspects, this invention relates to direct-positivephotographic emulsions and elements comprising fogged silver halidegrains and a compound which accepts electrons. In another of itsaspects, this invention relates to direct-positive photographic silverhalide emulsions and elements comprising reduction and gold foggedsilver halide grains which exhibit exceptional photographic speed.

It is known that direct-positive images can be obtained with certaintypes of photographic silver halide reversal emulsions. As shown inBritish Patent 723,019, published Feb. 2, 1955, one photographicemulsion of this type is a photographic emulsion comprising an electrontrapping compound and silver halide grains which are fogged using acombination of a reducing agent with a gold compound or a compound of ametal more electropositive than silver such as, for example, palladiumor platinum. However, in the past, the use of such a combination offogging agents has resulted in direct-positive photographic silverhalide emulsions which exhibit only low photographic speed, for example,photographic speed comparable to that obtained with the customary silverhalide emulsions used in enlarging papers and the like. It would, ofcourse, be very desirable to have available, direct-positivephotographic silver halide emulsions which comprise reduction and goldfogged silver halide grains and which also exhibit increasedphotographic speed in comparison to prior art materials.

Accordingly, it is an object of this invention to provide.direct-positive photographic emulsions exhibiting good photographicspeed.

Another object of this invention is to provide a means for obtainingfogged direct-positive photographic silver halide emulsions and elementswhich comprise silver halide grains having unique properties.

Still another object of this invention is to provide a means forobtaining fogged direct-positive photographic silver halide emulsionsand elements comprising electron trapping compounds such as cyaninedyes.

Still another object of this invention is to provide a means forobtaining an improved photographic reversal emulsion by combining a lowlevel of reduction fogging Patented Mar. 17, 1970 with a low level ofgold fogging of photographic silver halide grains.

Other objects and advantages of this invention will become apparent froman examination of the specification and claims which follow.

The above and other objects of this invention are obtained with foggedsilver halide grains characteristized by a rapid loss of fog uponbleaching in a chemical bleach and the use of such grains inphotographic emulsions, particularly direct-positive photographicemulsions comprising a compound which accepts electrons. The rapid fogloss which characterizes these silver halide grains can be illustratedby comparing (1) the density of processed direct-positive photographicemulsions comprising the fogged silver halide grains which are bleachedwith (2) identical processed emulsions which arenot bleached. Thedirect-positive photographic emulsions comprising the aforesaid grainscan be obtained by fogging photographic silver halide emulsions with areduction fogging agent in combination with a gold fogging agent at lowconcentrations.

One embodiment of this invention relates to a directpositivephotographic emulsion which comprises fogged silver halide grains and acompound which accepts electrons, said grains being such that a testportion thereof, when coated as a photographic silver halide emulsion ona support to give a maximum density of a least about one upon processingfor six minutes at about 68 F. in Kodak DK-SO developer, has a maximumdensity which is at least about 30% greater than the maximum density ofan identical coated test portion which is processed for six minutes atabout 68 F. in Kodak DK-SO developer after being bleached for about 10minutes at about 68 F. in a bleach composition of Potassium cyanide-50mg. Acetic acid (glacial)3.47 cc. Sodium acetate11.49 g. Potassiumbromide1l9 mg. Water to 1 liter.

Another embodiment of this invention relates to a photographic elementcomprising a support and at least one photographic silver halide. layerwhich comprises fogged silver halide grains and a compound which acceptselectrons, said grains being such that a test portion thereof, whencoated as a photographic silver halide emulsion on a support to give amaximum density of at least about one upon processing for six minutes atabout 68 F. in Kodak DK-SO developer, has a maximum density which is atleast about 30% greater than the maximum density of an identical coatedtest portion which is processed for six minutes at about 68 F. in KodakDK-SO developer after being bleached for about 10 minutes at about 68 F.in a bleach composition of:

Potassium cyanide-50 mg. Acetic acid(glacial)3.47 cc. Sodiumacetate-11.49 g. Potassium bromide-119 mg. Distilled water to 1 liter.

Another embodiment of this invention relates to a process whichcomprises contacting silver halide grains with about 0.001 to about 0.06rnilliequivalent per mole of silver halide of a reduction fogging agentand about 0.001 to about 0.01 millimole per mole of silver halide of agold fogging agent at a temperature in the range of about 40 to aboutC., the ratio of gold fogging agent to reduction fogging agent being inthe range of about 1:3 to about 20:1.

The silver halide grains disclosed herein can be fogged with acombination of a reduction fogging agent and a gold fogging agent. Inorder to obtain fogged silver halide grains which are characterized by arapid loss of fog upon bleaching, as disclosed herein, it is necessaryto employ a very low concentration of reduction fogging agent. It isknown that one equivalent weight of a reducing agent will reduce oneequivalent weight of silver halide to silver. In practicing thisinvention, much less than one equivalent weight of the reduction foggingagent is employed. Thus, less than about 0.06 milliequivalent ofreduction fogging agent per mole of silver halide is employed in foggingthe silver halide grains. Generally, about 0.0005 to about 0.06,preferably about 0.001 to about 0.03 milliequivalent of reductionfogging agent per mole of silver halide is employed in fogging thesilver halide grains in the practice of this invention. Prior artprocedures employing a combination of reduction and gold fogging agentshave employed concentrations of the fogging agents substantially inexcess of those employed herein and have obtained only very lowphotographic speeds. A preferred reduction fogging agent employed in thepractice of this invention is thiourea dioxide which is generallyemployed at a concentration in the range of about 0.05 to about 3,preferably about 0.1 to about 2 milligrams per mole of silver halide orabout 0.0005 to about 0.03 millimole per mole of silver halide. Stannouschloride is another suitable reduction fogging agent which can be usedin practicing this invention and can be used in concentrations in therange of about 0.05 to about 3 milligrams of stannous chloride per moleof silver halide. When higher concentrations of the reduction foggingagent, e.g., thiourea dioxide or stannous chloride are employed, theresult is a drastic reduction in photographic speed. Examples ofsuitable reduction fogging agents which can be employed in the practiceof this invention include hydrazine, phosphonium salts such as tetra(hydroxy methyl) phosphonium chloride, thiourea dioxide, as disclosed inHillson US. Patent 3,062,651, issued Nov. 6, 1962, and Allen et al., US.Patent 2,983,609, issued May 9, 1961, reducing agents such as thestannous salts, e.g., stannous chloride, as disclosed in Carroll US.Patent 2,487,850 issued Nov. 15, 1939, polyamines such as diethylenetriamine as disclosed in Lode et al., US. Patent 2,519,698, issued Aug.15, 1950, polyamines such as spermine as disclosed in Lowe et al., US.Patent 2,521,925, issued Sept. 12, 1950, bis( 3-aminoethyl)sulfide andits water soluble salts as disclosed in Lowe et al., US. Patent2,521,926, issued Sept. 12, 1950, and the like.

A gold fogging agent is used in combination with the low concentrationof reduction fogging agent to obtain the fogged silver halide grainsdescribed herein. The gold fogging agents employed can be any gold saltssuitable for fogging, as exemplified by the gold salts disclosed inWaller et al. US. Patent 2,399,083, issued Apr. 23, 1946, andDamschroder et al., US. Patent 2,642,361, issued June 16, 1953. Specificexamples of gold fogging agents are potassium chloroaurite, potassiumaurithiocyanate, potassium chloroaurate, auric trichloride,2-aurosulfobenzothiazole metho chloride, and the like. The concentrationof gold fogging agent employed in the practice of this invention issubject to variation but is generally in the range of about 0.001 toabout 0.01 millimole per mole of silver halide. Potassium chloroaurateis a preferred gold fogging agent and is most often used atconcentrations of less than about mg. per mole of silver halide, andpreferably at concentrations in the range of about 0.5 to about 4milligrams per mole of silver halide. The gold fogging agent oftencomprises a major portion of the fogging combination with the ratio ofgold fogging agent to reduction fogging agent generally being in therange of about 1:3 to about 20:1, often about 2:1 to about 20:1. Thesilver halide grains are preferably fogged using the reduction foggingagent initially and subsequently using the gold fogging agent. However,the reverse order of agents can be used or the reduction and goldfogging agents can be used simultaneously. The silver halide grains canbe fogged prior to coating or they can be coated prior to fogging. Thereaction conditions during fogging of the silver halide grains aresubject to wide variation although the pH is generally in the range ofabout 5 to about 7. The pAg is generally in the range of about 7 toabout9 and the temperature is generally in the range of about 40 to about 0.,most often about 50 to about 70 C. During fogging the silver halidegrains can be suspended in a suitable vehicle such as gelatin which isgenerally employed at a concentration in the range of about 50 to about200 grams per mole of silver halide.

As already indicated,'the foggcd silver halide grains described hereinare characterized by a rapid loss of fog upon chemical bleaching. Thegrains will lose at least about 25% and generally at least about 40% oftheir fog when bleached for ten minutes at 68 F. in a potassium cyanidebleach composition as described herein. This fog loss can be illustratedby coating the silver halide grains as a photographic silver halideemulsion on a support to give a maximum density of at least 1.0 uponprocessing for six minutes at about 68 F. in Kodak DK--50- developer andcomparing the density of such a coating with an identical coating whichis processed for six minutes at 68 F. in Kodak DK-50 developer afterbeing bleached for about 10 minutes at 68 F. in the potassium cyanidebleach composition. The maximum density of the unbleached coating willbe at least 30% greater, generally at least 60% greater, than themaximum density of the bleached coating. Kodak -DK50 developer isdescribed in the Handbook of Chemistry and Physics, 30th ed., 1947,Chemical Rubber Publishing Co., Cleveland, Ohio, p. 2558 and has thefollowing composition:

Water, about F. (52 C.)-500 cc. N-methyl-p-aminophenol sulfate2.5 gramsSodium sulfite, desiccated30.0 grams Hydroquinone2.5 grams Sodiummetaborate--10.0 grams Potassium bromide0.5

Water to make 1.0 liter.

The direct-positive photographic silver halide emulsions of thisinvention contain a compound which accepts electrons. Suitable electronaccepting compounds including the photoelectron accepting compounds ordesensitizing dyes used in photograpric reversal systems. Compounds ofthis type include the known desensitizers which trap electrons, asdisclosed in Britsish Patent 723,019, published Feb. 2, 1955. Theelectron acceptors which gave particular good results in the practice ofthis invention can be characterized in terms of their polarographichalfwave potentials, i.e., their oxidation reduction potentialsdetermined by polarography. Cathodic measurements can be made with a1X10- molar solution of the electron acceptor in a solvent, for example,methanol which is 0.05 molar in lithium chloride using a droppingmercury electrode with the polarographic halfwave potential for the mostpositive cathodic wave being designated E Anodic measurements can bemade with 1X10- molar aqueous solvent solution, for example methanolicsolutions of the electron acceptor which are 0.05 molar in sodiumacetate and 0.005 molar in acetic acid using a carbon paste of pyrolyticgraphite electrode, with the voltametric half peak potential for themost negative anodic response being designated E In each measurement,the reference electrode can be aqueous silyer-silver chloride (saturatedpotassium chloride) electrode at 20 C. Electrochemical measurements ofthis type are known in the art and are described in New InstrumentalMethods in Electrochemistry, by Delahay, Interscience Publishers, NewYork, N.Y., 1954; Polarography, by Kolthoff and Lingane, 2nd ed.,Interscience Publishers, New York, N.Y., 1952; Analytical Chemistry, 36,2426 (1964) by Elving; and Analytical Chemistry, 30, 1576 (1958) byAdams. Plus and minus signs are according to IUPAC (International Unionof Pure and Applied Chemistry) Stockholm Convention 1953. Compoundswhich can be employed as electron acceptors in the practice of thisinvention include organic compounds having an anodic polarographichalfwave potential (E,,) and a cathodic polarographic potential (E whichwhen added together give a positive sum. Preferably, such compounds alsospectrally sensitize photographic silver halide emulsion to radiationhaving a wavelength of at least about 480 my and generally spectrallysensitize such emulsions in the range of about 480 to about 800 Ill,u.Advantageously, these compounds provide spectral sensitization such thatthe ratio of minus blue relative speed to blue relative speed is greaterthan 7 and preferably greater than when exposed to a tungsten lightsource through Wratten No. 16 and No. 35 plus 38A filters respectively,and can be termed spectral sensitizing electron accep tors.

An especially useful class of electron accepting compounds which can beused in the direct-positive photographic silver halide emulsions of thisinvention are cyanine dyes, particularly imidazoquinoxaline dyes, suchas those described in Brooker et al., Belgian Patent 660,- 253,published Mar. 15, 1965. Very good results are obtained with cyaninedyes containing an indole nucleus aromatically substituted in the 2position, i.e., a cyanine dye containing a 2-aromatically substitutedindole nucleus. One useful class of spectral sensitizing, electronacceptors are the bis-( 1-alkyl-2-phenylindole-3)trimethine cyaninedescribed by Coenen et al., US. Patent 2,930,- 694, issued Mar. 29,1960. Another useful class of dimethine cyanine dyes of this type isdescribed in British Patent 970,601.

Still another class of useful spectral sensitizing electron acceptorsare the cyanine and merocyanine dyes in which at least one nucleus andpreferably two nuclei, contain densentizing substituents, such as N0e.g., 3,3- diethyl-6,6'-dinitrothiacarbocyanine chloride, as shown inBritish Patent 723,019.

The compounds which accept electrons in the directpositive photographicsilver halide emulsions of this invention can be employed in widelyvarying concentrations. However, such compounds are preferably employedat concentrations in the range of about 100 milligrams to about 2 gramsof electron acceptor per mole of silver halide. Specific examples ofsuitable electron acceptors include the following:

(1) 1,1-Dimethyl-2,2-diphenyl-3,3 -indolocarbocyanine bromide CH=CHOHNiPh Ph o I Br Me Me (2) 2,2'-Di-p-methoxyphenyll l'-dimethyl-3,3'-

indolocarbocyanine bromide CH=CHOH 1 IT N At? Br Me MeO (3) 1, l'-Dimethyl-2,2,8-triphenyl-3,3 '-indolocarbocyanine perchlorate ljronon- N Ph Ph l in Il /Ia 6 1,1',3, 3'-Tetraethylimidazo [4,5 -b]quinoxalinocarbocyanine chloride Additional examples include,phenosafranine, pinacreyptol yellow, S-m-nitrobenzylidenerhodanine,3-ethyl- 5 m nitrobenzylidenerhodanine,3-ethyl-5-(2,4-dinitrobenzylidene)-rhodanine, 5 onitrobenzylidene-3-phenylrhodanine, l',3-diethyl-6-nitrothia-2'-cyanineiodide, 4- nitro 6 chlorobenzotriazole, 3,3'-diethyl-6,6'-dinitro-9-phenylthiacarbocyanine iodide,Z-(p-dimethylaminophenyliminomethyl)benzothiazole ethoethyl sulfate,Crystal violet, 3,3'-diethyl-6,6'-dinitrothiacarbocyanine ethyl sulfate,1',3-diethyl-6-nitrothia-2'-cyanine iodide,1,3-diamino-5-rnethylphenazinium chloride,4-nitro-6-chlor0benzotriazole, 3,3-di-p-nitrobenzylthiaiarbocyaninebromide, 3,3-di-p-nitrophenylthiacarbocyanine iodide,3,3'-di-o-nitrophenylthiacarbocyanine perchlorate, 3, 3'-dimethyl-9-trifluoromethylthiacarbocyanine iodide, 9 (2,4dinitrophenylmercapto)-3,3'-diethylthiacarbocyanine iodide, bis(4,6-diphenylpyryl-2)trimethincyanine perchlorate,anhydro-2-p-dimethylaminophenyliminomethyl 6-nitro-3-(4-sulfobutyl)benzothiazolium hydroxide,1-(2-benzothiazolyl)-2-(p-dimethylaminostyryl) 4,6 diphenylpyridiniumiodide, 1,3 -diethyl-5-[ 1,3-neopentylene-6-( 1,3,3-trimethyl-2-indolinylidene)-2,4-hcxadienylidene] 2 thiobarbituric acid,2,3,5-triphenyl-2H-tetrazolium chloride, 2-(4-iodophenyl) -3-(4-nitrophenyl -5-phenyl-tetrazolium chloride,1-methyl-8-nitroquinolinium methyl sulfate, 3,6-bis[4-(3-ethyl-Z-benzothiazolinylidene) 2 butenylidene]1,2,4,5-cyclohexanetetrone and the like.

The silver halides employed in the preparation of the photographiccompositions described herein include any of the photographic silverhalides as exemplified 'by silver bromide, silver iodide, silverchloride, silver chlorobromide, silver bromoiodide, silverchlorobromide, and the like. Silver halide grains having an averagegrain size less than about one micron, preferably less than about 0.5micron, give particularly good results. The silver halide grains can beany suitable shape such as cubic or octahedral and preferably have arather uniform diameter frequency distribution. For example, at least byWeight, of the photographic silver halide grains can have a diameterwhich is within about 40%, preferably within about 30% of the mean graindiameter. Mean grain diameter, i.e., average grain size, can bedetermined using conventional methods, e.g., such as by projective areaas shown in an article by Trivelli and Smith entitled EmpiricalRelations Between Sensitometric and Size-Frequency Characteristics inPhotographic Emulsion Series in The Photographic Journal, vol. LXXIX,1939, pp. 330-338. The fogged silver halide grains in thedirect-positive photographic emulsions of this invention produce adensity of at least 0.5 when developed without exposure for five minutesat 68 F. in Kodak DK-50 developer when such an emulsion is coated at acoverage of 50 to about 500 mg. of silver per square foot of support.The preferred photographic silver halide emulsions comprise at least 50mole percent bromide, the most preferred emulsions being silverbromoiodide emulsions, particularly those containing less than about tenmole percent iodide. The photographic silver halides can be coated atsilver coverages in the range of about 50 to about 500 milligrams ofsilver per square foot of support.

Various colloids can be used as vehicles or binding agents in thedirect-positive photographic materials of this invention. Satisfactorycolloids which can be used for this purpose include any of thehydrophilic colloids generally employed in the photographic field,including, for example, gelatin, colloidal albumin, polysaccharides,cellulose derivatives, synthetic resins such as polyvinyl compounds,including polyvinyl alcohol derivatives, acrylamide polymers and thelike. In addition to the hydrophilic colloids, the vehicle or bindingagent can contain dispersed polym- 8 Patent 2,271,623, issued Feb. 3,1942; U.S. Patent 2,275,727, issued Mar. 10, 1942; U.S. Patent2,787,604, issued Apr. 2, 1957; U.S. Patent 2,816,920 issued Dec. 17,1957; U.S. Patent 2,739,891, issued Mar. 27, 1956 and Belgian Patent652,862.

erized vinyl compounds, particularly those which increase This inventioncan be further illustrated by the followthe dimensional stability ofphotographic materials. Suiting examples of preferred embodimentsthereof although able compounds of this type include water-insolublepolyit will be understood that these examples are included mers of alkylacrylates or methacrylates, acrylic acid, sulmerely for purposes ofillustration and are not intended foalkyl acrylates or methacrylates,and the like. 10 to limit the scope of the invention unless otherwisespecif- The photographic compositions described herein can be icallyindicated. coated on a wide variety of supports in preparingphotographic elements. The photographic silver halide emul- EXAMPLE 1sions can be coated on one or both sides of the support Thedirect-positive ph p Silver halide emulwhich is preferably transparentand/or flexible. Typical sions of this invention comprise silver halidegrains supports are cellulose nitrate film, cellulose acetate film,characterized by a rapid 1088 Of fog P Chemical bleachpolyvinyl acetalfilm, polystyrene film, polyethylene tering. Furthermore, lowconcentrations of reduction and ephthalate film and other polyester filma well as glass, 30 d f gging agents are used in Order to Obtain suchpaper, metal, wood and the like. Supports such as paper silver halidegrains. To illustrate these features, a medium Which are coated withu-olefin polymers, particularly poly- 2 grain photographic gelatinosilver bromoiodide emulsion mers of oc-OlCfiIlS containing two or morecarbon atoms, containing approximately one mole percent iodide is preasexemplified by polyethylene, polypropylene, ethylenepared using theprocedure described for Emulsion No. 10 butene copolymers, and the like,give good results. in the Trivelli and Smith article entitled, EmpiricalRe- The photographic silver halide emulsion and other laylations BetweenSensitometric and Size-Frequency Charers present in the photographicelements made according acteristics in Photographic Emulsion Series,published in to this invention can be hardened with any suitable hard-The Photographic Journal, vol. LXXIX, May 1939 (PP. ener, includingaldehyde hardeners such as formaldehyde 330338), except that theemulsion is not chemically and mucochloric acid, aziridine hardeners,hardeners sensitized, i.e., the second ripening is omitted. The avwhichare derivatives of dioxane, oxypolysaccharides such erage grain size ofthis emulsion is about 0.4 micron. The as oxystarch or oxy plant gums,and the like. emulsion. A sample of each portion of the emulsion is Thephotographic silver halide emulsion layers can conis reduction and goldfogged by simultaneously adding tain additional additives, particularlythose known to be a reducing agent with a gold salt and heating theemulbeneficial in photographic emulsions, including, for examsion at 65C. for 50 minutes using the fogging agent ple, lubricating materials,stabilizers, speed increasing rnaconcentrations listed in the followingTable l. 1.5 g. of terials, absorbing dyes, plasticizers, and the like.These an electron accepting compound (pinacryptal yellow) perphotographic emulsions can also contain spectral sensimole of silverhalide is added to each portion of the tizing dyes in addition to theelectron accepting comemulsion. A simple of each portion of the emulsionis pounds which can spectrally sensitize in some cases. coated onconventional cellulose acetate film support at Suitable spectralsensitizers include the cyanines, merocoverages of 230 mg. of silver and745 mg. of gelatin cyanines, complex(trinucleaflcyanines,complex(trinuper square foot of support. A sample of each coatingclear)merocyanines, styryls and hemicyanines. Furtheris exposed on anEastman Ib sensitometer, developed more, these emulsions can containcolor forming couplers for 6 minutes in Kodak DK-SO developer, fixed,washed or can be developed in solutions containing couplers or anddried. The maximum density, photographic speed other color generatingmaterials. The color forming at a given density below maximum density,and gamma couplers can be incorporated into the direct positive photoaredetermined using the same procedure for each coating graphic silverhalide emulsion using any suitable tech- .of the emulsion portions. Theresults are as follows:

TABLE 1 Reducing Agent Gold Fogging Agent Mg./mole Mg./mo1e Rel. CoatingCompound Agz Compound Agr D Speed 7 1 Thiourea dioxide 0.4 Potassiumchloro 2.0 1. 74 11,000 2.38

aurate. 2 d0 0.75 do 7.5 1. 80 316 1. s0 3 do 1.5 ..do 15.0 1.82 1451.78 4 Stannous chloride 1.5 Auric trichloridemn 15.0 1.80 100 1. 45

nique, e.g., techniques of the type shown in Jelley et al., It can beseen from the above results the reduction U.S. Patent 2,322,027, issuedJune 15, 1943; Fierke et al., fogging agent and the gold fogging agentcombination U.S. Patent 2,801,171, issued July 30, 1957; and Fischer isemployed at low concentrations (Coating No. l) in U.S. Patents 1,055,155and 1,102,028, issued Mar. 4, 1913 order to obtain the direct-positivephotographic silver and June 30, 1914, respectively, and Wilmanns U.S.Pathalide emulsions of this invention which exhibit a truly tent2,186,849, issued Jan. 9, 1940. They can also be dephenomenal increasedphotographic speed. When the veloped using incorporated developers suchas polyhyabove procedure is repeated using stannous chloride withdroxybenzenes, aminophenols, 3-pyrazolidones, and the auric trichlorideat the low concentrations given for Coatlike. ing No. 1 a comparablespeed is obtained.

It is sometimes advantageous to include surface active The rapid loss offog upon chemical bleaching of the agents or compatible mixtures of suchagents in the prepfogged silver halide grains disclosed herein isillustrated aration of the photographic materials described herein. bybleaching a sample of each of the above coated Suitable agentsof thistype include the non-ionic, ionic emulsion portions before developmentin a chemical and amphoteric types, as exemplified by polyoxyalkylenebleach having the following composition: derivatives, amphoteric aminoacid dispersing agents, including sulfobetaines, and the like. Suchsurface active Potassium cyanide50 mg. agents are described in U.S.Patent 2,600,831, issued June Acetic acid (glacial)--3.47 cc.

17, 1952; U.S. Patent 2,271,622, issued Feb. 3, 1942; U.S. Sodiumacetatel1.49 g.

Potassium bromide1 19 mg. Water to 1 liter.

The films are bleached for ten minutes at 68 F. in the above bleachwithout agitation. Coatings are then washed in running water for tenminutes and allowed to dry at room temperature. The coatings are thendeveloped for 6 minutes in Kodak DK-SO developer, fixed, washed anddried in the conventional manner. The results obtained are set forth inthe following Table 2.

TABLE 2 Dmax. before Dmnx. after Percent Loss Coating bleachingbleaching in Dmnx.

Similar results are obtained when the above procedure is repeated withreduction fogging agents such as hydrazine, tetra(hydroxymethyl)phosphonium chloride, triethylene tetramine, and gold foggingagents such as potassium aurithiocyanate and 2-aurosulfobenzothiazolemetho chloride.

Example 2 As previously indicated, the reduction fogging agent and goldfogging agent can be added in a stepwise manner. Furthermore, anincrease in the concentration of reduction fogging agent reducesphotographic speed. To illustrate each of these features, a fine grainsilver bromoiodide emulsion is prepared according to the proceduredescribed for Emulsion No. 9 in the T'rivelli and Smith article referredto in Example 1. The average grain size of the silver halide in thephotographic emulsion is about 0.2 micron. The resulting emulsion issplit into two portions which are fogged by first adding thioureadioxide and heating for 60 minutes at 65 C. and then adding potassiumchloroaurate and heating the emulsion for 80 minutes at 65 C. with theconcentrations of fogging agent listed in the following Table 3. Anelectron accepting compound (5-1n-nitrobenzylidenerhodanine) isincorporated into each portion of the emulsion at a concentration of 0.2g./mo1e of silver halide. Each portion direct-positive silver halideemulsions. It can be seen from the above table that the photographicemulsions described herein exhibit photographic speeds up to 20 timesthat of such prior art materials. Furthermore, it has been found thatthe ratio of reduction fogging agent to gold fogging agent has asignificant effect upon the photographic speed of the direct-positivephotographic silver halide emulsions disclosed herein. Thus, when theratio of gold fogging agent to reduction fogging agent in the aboveprocedure is increased to about 25:1, the photographic speed is reducedby over EXAMPLE 3 As previously indicated, spectral sensitizing dyeswhich are not electron acceptors can be incorporated into thedirect-positive photographic silver halide emulsions of this invention.To illustrate, a reduction-gold fog-ge d emulsion is prepared asfollows: A silver bromoiodide gelatin emulsion containing approximately2.5 mole percent iodide and having an everage grain size of about 0.2micron is prepared by adding an aqueous solution of potassium bromideand potassium iodide, and an aqueous solution of silver nitrate,simultaneously to a rapidly agitated aqueous gelatin solution at atemperature of 70 C., over a period of about 35 minutes. The emulsion ischill-set, shredded and washed by leaching with cold water in theconventional manner. The emulsion is reduction gold fogged by firstadding 0.2 mg. of thiourea dioxide per mole of silver halide and heatingfor minutes at 60 C. and then adding 0.4 mg. of potassium chloroanrateper mole of silver halide and heating for 60 minutes at C. 0.2 g. permole of silver halide of S-m-nitro-benzylidenerhodanine is added to thefog-ged emulsion. The emulsion is spectrally sensitized with thesensitizing dyes listed in the following Table 4. Portions of theemulsion are coated on cellulose acetate film support at a coverage of100 mg. of silver and 400 mg. of gelatin per square foot of support. Thecoated samples are exposed for 10 seconds on an Eastman I bsensito-meter to light from a tungsten source modulated by a continuouswedge and a Wratten No. 16 filter to demonstrate spectral sensitivity.The film samples are developed for five minutes in Kodak DK-SOdeveloper, fixed, washed and dried in the usual manner. The results areas follows:

TABLE 4 Wratten N o. 16 Filter White Light Exposure Exposure (Minus BlueExposure) I maz. Rel. Rel. Sample Sensitmng Dye (gJmole Age) Dmin, SpeedDm D Speed Nonoe 1. 46 04 363 1. 4 1. 34 1 Anhydro-1-ethyl-1-(4-suli'obutyD-2, 2-

cyanine hydroxide (0.2).

4-[ (1-ethy1-2(1H)-naptho[1, 21thiazolylidene)isopropylidene]3-methyl-1-(psulfophenyl)-2-pyrazolin-5-one (0.14).Anhydro-1-ethyl-3-(3-suli0butyl)-thia- 0. 98 0. 2 1, 070 79 02 5132-cyanine hydroxide (0.7).

0 EXAMPLE 4 of the emulsion is coated on conventional cellulose acetatefilm support at a coverage of 100 mg. of silver and 350 mg. of gelatinper square foot of support. A sample of each coating is exposed andprocessed as described in Example 1. The results are as follows:

The photographic speed of Coating No. 2 in the above procedure iscomparable to that of a conventional type enlarging paper and isillustrative of the photographic Color forming couplers can beincorporated into the direct-positive photographic silver halideemulsions described herein. To illustrate, the dyes indicated in thefollowing Table 5 are added to samples of the reduction and gold foggedsilver bromoiodide emulsion of Example 3 which contains the electronacceptor S-m-nitrobenzylidenerhodanine. The emulsion is then digestedfor ten minutes at 52 C. Coupler dispersions melted at 40 C. are addedto the emulsion where indicated in the following Table 5. The emulsionsare cooled to 40 C. coated on conventional cellulose acetate filmsupport, chill-set and dried as in Example 3. The film coatings areexposed and processed as indicated in the following table to give speedexhibited by prior art reduction and gold fogged reversal images incolor.

TABLE 5 9% R 0 ye of fiiis i- Formed by Type of Coating Dye (g./mole)tization Color Forming Coupler Exposure Coupler Process Blue--benzoyl-3-[u.-(2 4-di-amyl- Tungsten source Yellow A 1 None phenoxy)butrarnide} Wratten No.

Q-methoxyacetanilide T35+3t8A filter. 2 Anh dro-1-etli 1-3- 3- Green1-(2 4 G-trichloroungs .en source suI i obutyl) thia-ycyaninephe'nyl)-3,3'(2,4- Wratten No. Magenta.-. A hydroxide (0.2)+di-t-arnylphenoxy-acet- 61+16 filter. anhydro-1-ethyl-Y-(4- amide)benzimidazosuliobutyl) -2,2-cyanine 5-pyrazolone. hydroxide (0.2). 33,3-dimethyl-8,10-di- Red 5-[a(2,4-d1-t-amyl Tungsten source Cyan. A

(m-toloxy)thiacarbophenoxy)hexanam1do]: Wratten No. 29 filter. .cyaninebromide (0.2) 2-ll1ieptitfluorobutyram1dop eno l-hydroxy-2[ 0.- (2,4-

di-t-amylphenoxy-nbutyl)[naphl(;hamide. D 1 ht Q m d B -d eth l-8,l0 di-Red. 1-hydroxy-l-[{i- 2- ay ig ua y source o- 4" zirit c i loxyltliiaoarboacetoamidohphenethyl} Wratten No. 16 filter.

oyanine bromide (0.2). naphthalamide.

l 1 0 ss as described in Graham et al. U.S. Patent 3,046 129, issuedJuly 24 1962 in Example (a) (col. 27 lines et seq except that bl ck fidv vlii i velopment is omitted and the color development is reduced to 1mlniite and done in total darkness until after fixing. 4

B-Color process for developing cyan dye images as described in Vittum etal. U.S. Patent 3,002,836 1ssued Oct. 3, 1961 in Example III (col. 4,lines et seq.) except that black-and-white (MQ) development is omitted.

Thus, by the practice of this invention there is provideddirect-positive photographic silver halide emulsions exhibitingexcellent photographic speed. Such emulsions can be prepared using goldfogging agents in combination with reduction fogging agents at lowconcentrations. However, in some applications where the same speedcharacteristics are not required, other fogging agents can besubstituted for the gold fogging agent. Suitable agents of this typeinclude, for example, compounds of metals which are more electropositivethan silver, including, e.g., platinum, palladium and other noble metalcompounds. Due to their unique photographic speed, the direct-positivephotographic silver halide emulsions disclosed herein are particularlyuseful in a variety of applications in the photographic field. Forexample, they can be used in lithographic printing plates, particularlythose of the type disclosed in U.S. Patent 3,146,104, issued Aug; 25,1965, color transfer materials, direct reversal color processes,duplicating film, e.'g. microfilm, etc. If desired, the silver halidegrains can be gold fogged using special processing techniques, forexample, a coating of a reduction fogged silver halide emulsioncontaining an electron accepting compound can be exposed and bathed in asolution of a gold salt such as gold thiocyanide which can contain asmall concentration, for example, less than about 0.5%, of a halogensuch as bromide. The coating can then be processed in an alkalinedeveloper such as Kodak DK or Kodak DK-l9 developer for 5-10 minutes.Another interesting reversal system involves developing, in a foggingdeveloper, a photographic silver halide emulsion which has been treatedwith a reduction fogging agent such as stannous chloride. This systeminvolves exposing and developing the aforesaid photographic emulsion inan alkaline fogging developer such as Kodak DK--50 developer to whichsmall concentrations, for example, up to about 0.2 gram per liter, oftriethylenetetramine and 1-phenyl-3-pyrazolidone have been added toobtain a reversal image.

The fogged direct-positive photographic silver halide emulsionsdescribed herein can also be used in negative azo dye image formation.The art of bleaching an azo dye by chemistry involving the oxidation ofmetallic silver is well known. In such methods an azo dye in a coatingcontaining a stepwise image of metallic silver is bleached proportionalto the silver under strongly acidic conditions giving a reversal imagein dye. Bleaching rates are enhanced by accelerators such as2-hydroxy-3-amino phenazine or anthraquinone-B-sulfonic acid as shown,for example, at p. 643 of Photographic Chemistry, England languageedition, vol. 2 by Pierre Glafkides. This type of bleaching process canemploy a very fine grain directnositive photographic silver halideemulsion of the type described herein. Exposure, development in analkaline developer such as Kodak DK-SO developer and fixation give adirect-positive silver image with no effect on the azo dye. Conventionaldye-bleaching, silver bleaching and fixation then give a dye imagereversal of the silver image and also a dye reversal of the originalsubject with an excellent ratio of Dmax, to D As shown herein, colorforming couplers can be incorporated into the direct-positivephotographic silver halide emulsions of this invention. It has beenfoundthat the incorporation of a color forming coupler or coupler solvent inthe emulsion significantly improves the quality of the reversal obtainedin black and white elonhydroquinone type developers. There is obtainedan increase in contrast and a lower minimum density using this typedeveloper with such emulsions.

The fogged, direct-positive photographic silver halide emulsions canalso be used in color diifusion transfer systems in combination with dyedevelopers. Photographic developers which contain a dye moiety can, ofcourse, be synthesized. Upon applying an alkaline solution to animagewise exposed negative developing silver halide emulsion elementcontaining one of these dye developers, the dye developer becomesimmobilized within the element where development occurs, that is, in theexposed areas. When an alkaline treated sample of this material isbrought into contact with a receiver sheet, there is obtained a positivetransfer print composed of transferred dye-developer and a negativeprint composed of nontransferred dye developer when the negative silverimage is bleached. Dye developer coatings made with a reversal emulsionof the type disclosed hereinwill develop to yield a positive silverimage. Therefore, an alkaline treated sample of this material brought incontact with a receiver will yield a negative dye transfer printcomposed of transferred dye-developer and a positive print composed ofnon-transferred dye-developer when the positive silver image isbleached.

The fogged, direct-positive photographic silver halide emulsions of thisinvention can also be used in reversal chemical transfer systems. Thechemical transfer system is often used for making positive copies frompositive originals and is very popular since stable right-reading imagesare readily obtained. The negative is exposed in a normal manner, thenpassed through a solvent developer in contact with a nucleated receiver.The exposed negative silver is developed, while the unexposed silverhalide dissolves and diffuses to the receiver sheet where it isdeposited on the nuclei and developed. The chemical transfer print canbe obtained in a short time since no additional processing steps arenecessary. The fogged, direct-positive photographic silver halideemulsions of this invention, upon exposure to a negative image, followedby development, give a negative silver image in the emulsion layer. Inthe presence of a solvent developer, the exposed silver halide which hasnot developed, migrates to the nucleated receiver where it is depositedas a positive image. The emulsions of this invention can be used inchemical transfer processes employed to make a chemical transfer printby either the one-sheet system, in which the emulsion is coated on thesame support as the receiver layer, or by the two-sheet system, in whichthe emulsion and receiver layers are coated on separate supports.

The direct-positive photographic silver halide emulsions of thisinvention can also be processed in the presence of ammonia vapors orother gaseous compounds of the type disclosed in US. Patent 3,158,481,issued Nov. 24, 1964; US. Patent 3,144,334, issued Aug. 11, 1964, andBritish Patent 973,965, published Nov. 4, 1964. The developing agent canbe incorporated into the emulsion coating or in a separate sheet.Ammonia or another gaseous compound which is used to activate thecoating can be incorporated in a separate layer of the elementcontaining the emulsion. The ammonia or other activator can be in anysuitable form, for example, in the form of an ammonia polymer. Suchactivating materials can also be incorporated in a sheet separate fromthe element containing the emulsion and activated by heat. Processingwith ammonia or other activators is of special interest in the documentcopying field where the emulsion is coated on paper or as a filmduplicating material where the emulsion is coated on film.

Although the invention has been described in considerable detail withreference to certain preferred embodiments thereof, it will beunderstood that variations and modifications can be eifected withoutdeparting from the spirit and scope of the invention as describedhereinabove and as defined in the appended claims.

I claim:

1. A direct-positive, photographic emulsion which comprises fo'ggedsilver halide grains and an organic desensitizer. which has an anodicpolarographic half-wave potential and a cathodic half-wave potentialwhich, when added together, give a positive sum, said grains being suchthat a test portion thereof, when coated as a photographic silver halideemulsion on a support to give a maximum density of at least about 1 uponprocessing for 6 minutes at about 68 F. in Kodak DK-SO developer, has amaximum density which is at least about 30% greater than the maximumdensity of an identical coated test portion which is processed for 6minutes at about 68 F. in Kodak DK-SO developer after being bleached forabout 10 minutes at about 68 F. in a bleach composition of:

Potassium cyanide-50 mg. Acetic acid (glacial)3.47 cc. Sodiumacetate-41.49 g. Potassium bromide1l9 mg. Water to 1 liter.

2. The photographic emulsion of claim 1 in which the grains are foggedwith about 0.0005 to about 0.06 milliequivalent per mole of silverhalide of a reduction fogging agent and about 0.001 to about 0.01millimole per mole of silver halide of a gold fogging agent.

3. The photographic emulsion of claim 1 in which the silver halidecomprises at least 50 mole percent bromide and the silver halide grainsare fogged with about 0.0005 to about 0.06 milliequivalent per mole ofsilver halide of a reduction fogging agent and about 0.001 to about 0.01millimole per mole of silver halide of a gold fogging agent, the ratioof gold fogging agent to reduction fogging agent being in the range ofabout 1:3 to about 20: 1.

4. The photographic emulsion of claim 1 in which the silver halidegrains have an average grain size less than about 1 micron and arefogged with a reduction fogging agent and a gold fogging agent.

5. The photographic emulsion of claim 1 in which the silver halidegrains have an average grain size of less than about 1 micron, arefogged with a reduction fogging agent and a gold fogging agent and saiddesensitizer is an organic compound which spectrally sensitizes in therange of about 480 to about 800 mg.

6. The photographic emulsion of claim 2 in which said desensitizer is acyanine dye.

7. The photographic emulsion of claim 1 which contains a spectralsensitizing dye in addition to said desensitizer.

8. The photographic emulsion of claim 2 in which said desensitizer is animidazoquinoxaline dye.

9. The photographic emulsion of claim 6 in which the silver halide issilver bromoiodide comprising at least 50 mole percent bromide and lessthan about 10 mole percent iodide.

10. A photographic element comprising a support and at least onephotographic silver halide layer which comprises fogged silver halidegrains and an organic desensitizer which has an anodic polarographichalf-wave potential and a cathodic half-wave potential which, when addedtogether, give a positive sum, said grains being such that a testportion thereof, when coated as a photographic silver halide emulsion ona support to give a maximum density of at least about 1 upon processingfor 6 minutes at about 68 F. in Kodak DK-SO developer, has a maximumdensity which is at least about 30% greater than the maximum density ofan identical coated test portion 'which is processed for 6 minutes atabout 68 F. in Kodak DK-SO developer after being bleached for about 10minutes at about 68 F. in a bleach composition of:

Potassium cyanide-50 mg. Acetic acid (glacial)--3.47 cc. Sodiumacetate-11.49 g. Potassium bromide119 mg. Distilled water to 1 liter.

11. The photographic element of claim 10 in which the silver halidegrains are fogged with a reduction fogging agent and a gold foggingagent.

12. The photographic element of claim 11 in which the concentration ofgold fogging agent is in the range of about 0.001 to about 0.01millimole per mole of silver halide.

13. The photographic element of claim 11 in which the silver halidecomprises at least 50 mole percent bromide and the silver halide grainsare fogged with about 0.0005 to about 0.06 milliequivalent per mole ofsilver halide of the reduction fogging agent and about 0.001 to about0.01 millimole per mole of silver halide of the gold fogging agent.

14. The photographic element of claim 10 in which the silver halide issilver bromoiodide comprising at least 50 mole percent bromide and up toabout 10 mole percent of iodide.

15. The photographic element of claim 11 in which the photographicsilver halide layer is a gelatin photographic silver halide layer.

16. The photographic element of claim 10 in which the silver halidegrains are fogged with a reduction fogging agent and a gold foggingagent, the photographic silver halide layer is a gelatin photographicsilver halide layer and the silver halide grains have an average grainsize up to about 1 micron.

17. The photographic element of claim 10 in which the silver halidegrains are fogged with a reduction fogging agent and a gold foggingagent and said desensitizer is an organic compound which spectrallysensitizes in the range of about 480 to about 800 mg and comprises,contiguous to the silver halide grains, a color-forming coupler.

18. The photographic element of claim 10 in which the silver halidegrains are fogged with about 0.0005 to about 0.06 milliequivalent permole of silver halide or a reduction fogging agent and about 0.0001 toabout 0.01

millimole per mole of silver halide of a gold fogging agent, the ratioof gold fogging agent to reduction fogging agent being in the range of1:3 to about 2021, the silver halide comprises at least about 50 molepercent bromide and said desensitizer is a cyanine dye.

19. The photographic element of claim 18 in which the cyanine dye isanimidazoquinoxalinedye.

20. The photographic element of claim 18 in which the silver halide is asilver bromoiodide which comprises at least 50 mole percent bromine andup to about 10 mole percent iodine.

21. The photographic element of claim 18 in which the reduction foggingagent is thiourea dioxide and the gold fogging agent is potassiumchloroaurate.

22. The photographic element of claim 18 in which the reduction foggingagent is thiourea dioxide, the gold fogging agent is potassiumchloroaurate and the silver halide is silver bromoiodide which comprisesat least 50 mole percent bromine and up to about 10 mole percent iodine.

23. The process which comprises contacting silver halide grains withabout 0.0005 to about 0.06 milliequivalent per mole of silver halide ofa reduction fogging agent and about 0.001 to about 0.01 millimole permole of silver halide of-a gold fogging agent at a temperature in therange of about 40 to about 100 C., the ratio of gold foggin'g agent toreduction fogging agent being in the range of about 1:3 to about :1.

24.The process of claim 23 in which the silver halide comprises at least50 mole percent bromide.

25. The process of claim 23 in which the silver halide has an averagegrain size up to about 1 micron.

26. The process of claim 23 in which the silver halide grainsarecontacted with the reduction fogging agent and are subsequentlycontacted with the gold fogging agent.

27. The process of claim 23in which the reduction fogging agent isthiourea dioxide and the gold fogging agent is potassium chloroaurate.

. 28. The process of claim 23 comprising adding a desensitizer compoundto the silver halide grains after they' have been contacted with thereduction and gold fogging agents.

29. Fogged, photographic silver halide grains being such that a testportion thereof, when coated as a photographic silver halide emulsion ona support to give a maximum density of i at least about 1 uponprocessing f or 6 minutes at about 68 F. in Kodak DK-50 developer, has amaximum density which is at least about 30% greater than the maximumdensity of an identical coated test portion which is processed for 6minutes at about 68 F. in Kodak DK-SO developer after being bleached forabout 10 minutes at about 68 F. in a bleach composition of:

Potassium cyanide50 mg.

Acetic acid (glacial)3.47 cc.

Sodium acetate-11.49 g.

Potassium bromide1 19 mg. Water to 1 liter.

30. The photographic silver halide grains of claim 29 per mole of silverhalide of a reduction foggingagent and about 0.001 to about 0.01millimole per mole of silver halide of a gold fogging agent.

31. The photographic silver halide grains of claim 29 in which thesilver halide comprises at least 50 mole percent bromide and the grainsare fogged with about 0.0005 to about 0.06 milliequivalent per mole ofsilver halide of a reduction fogging agent and about 0.001 to about 0.01millimole per mole of silver halide of a gold fogging agent, the ratioof gold fogging agent to reduction fogging agent being in the range ofabout 1:3 to about 20:1. 32. The photographic silver halide grains ofclaim 31 having an average grain size less than about one micron. v 33.The photographic silver halide grains of claim 29 wherein said grainsare fogged with about 0.0005 to about 0.06 milliequivalent per mole ofsilver halide of a reduction fogging agent and about 0.001 to about 0.01millimole per mole of silver halide of a gold fogging agent and havingan organic desensitizer compound adjacent said grains which has ananodic polarographic half-wave potential and a cathodic half-wavepotential which, when added together, give a positive sum.

34. A direct-positive, photographic emulsion which comprises foggedsilver halide grains and a desensitizer which has an anodicpolarographic half-wave potential and a cathodic half-wave potentialwhich, when added together, give a positive sum, said grains being suchthat a test portion thereof, when coated as a photographic silver halideemulsion on a support to give a maximum density of at least about 1 uponprocessing for 6-minutes at about 68 F. in Kodak DK-SOdeveloper, has amaximum density which is at least about 30% greater than the maximumdensity of an identical coatedtest portion which is processed for 6minutes at about 68 F. in Kodak DK-SO developer after being bleached forabout 10 minutes at about 68 F. in a bleach composition of:

Potassium cyanide-50 mg. Acetic acid (glacial)3.47 cc. Sodiumacetate-11.49 g. Potassium bromide-119 mg. Water to 1 liter.

References Cited FOREIGN PATENTS 723,019 2/1952 Great Britain.

NORMAN G. TORCHIN, Primary Examiner 1 R. E. FIGHTER, Assistant Examinerw UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,501,307 Dated March 17, 1970 Inventor(s) Bernard D. Illingsworth It iscertified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

r C olumn 2, line 7, "characteristized" should read characterize-H'lColumn 3, line M2, "Lode" should read -Lowe--. Column 14., line 141+,"photograpric" should read photographic--. Column 5, line 7, "emulsion"should read --emulsions--; line 28, "cyanine" should read --cyanines--;line 35, "desentizing" should read desensitizing-. Columns 5-6, extremeright portion of each formula,

(3 should read Q Column 6, lines 1 2-13, "pinacreyptol" should readpinacryptol line 23, that portion of formula set forth as"-nitrobenzylthiaiarbocyanine" should read nitrobenzylthiacarbocyanineColumn 8, line 30, delete A sample of each portion of the emulsion is"and insert --is divided into several portions and each portion-; line37, "simple" should read --sample--. Columns 9-10, Table L under headingsensitizing Dye (g./mole Agx), for Sample 1 "Nonoe" should read--none--. Columns 11- 12, Table 5, under heading Dye (g./mole), forCoating 14., that part of formula set forth as 8,1 O,di-" should read8,1 O-diunder heading Color Forming Coupler, for Coating 1 that part offo rmula set forth as "butramidg7-" should read butyramidg/- for Coating2, that part of formula set forth as 3, 3' (2",L should read 3,3 -(2",L4for Coating 3, that part of formula set forth as "butyl)L should readbutylF- for Coating L that part of formula set forth as "-acetoamido)-"should read -acetamido)- Column 114., line 75, "0.0001 should read--0.001 Column 15, line 7, "animidazoquinoxalinedye" should read animidazoquinoxaline dye.

SIGNED AND SFM EU Axum M wmmu E. m. Anmi ()ffi Gems-1mmor Paton"

